Fibre for an Acoustic Insulating Material, Especially for Sound Dampers Compressed Air Devices

ABSTRACT

An acoustic insulating material, especially for a sound damper in compressed air devices, is provided which includes fibres of a thermoplastic material comprising structures or profiled elements which are moulded or embossed in the surfaces thereof and which raise the surfaces or specific surfaces thereof. The fibres are processed to form braided or woven tubing, the ends thereof being welded such that an approximately rectangular tubular section is created, forming the acoustic insulating material when rolled into a woven tubular element.

BACKGROUND OF THE INVENTION

The present invention relates to a new acoustic insulating material, especially for sound dampers in compressed air devices.

From DE 10248183 A1, for example, it is known that insulating materials can be used in the form of a knitted fabric roll in sound dampers of compressed air devices. Such a knitted fabric roll is made from a tubular knitted fabric produced on a circular knitting machine from warp knit thermoplastic fibres having, for example, rectangular cross section, by cutting a knitted fabric tube to a predetermined length and heat sealing it at its cut faces in such a way that a rectangular tubular portion is obtained. This rectangular tubular portion is then rolled up to obtain a knitted fabric roll. The knitted fabric roll is then pushed into a connecting tube leading to the atmosphere. Aside from the fact that it is necessary to use an additional connecting tube, which requires a large amount of installation space, and that it is necessary to take additional measures to ensure that the knitted fabric roll is held sufficiently in place in the connecting tube, the resulting sound damping is not satisfactory.

DE 42 37 630 A1 describes a compressed air venting device that has a primary air path routed from an inlet of a housing via noise damping means to an outlet, and a secondary air path provided parallel thereto and comprising a first sub-channel extending from the inlet and a second sub-channel formed by the outlet or leading to the outlet. The two sub-channels are not filled with the noise damping means. The two sub-channels are in communication with one another via the noise damping means. The two sub-channels and that part of the noise damping means which places the two sub-channels in communication are arranged in such a way that such part of the noise damping means opens up a direct communication path between the two sub-channels when a dynamic pressure is admitted. The noise damping means are formed by a filtering knitted fabric, which comprises a stocking-like woven part of plastic flat wire, which is wound in the form of a roll. The housing is composed of one housing part resembling a pot and another housing part formed as a cover to be snapped thereon. A disadvantage of this compressed air venting device used as a sound damper is that the danger of leaks causing a loud noise level exists at the joints of the housing parts. Moreover, the known device is relatively bulky, and therefore requires considerable installation space.

SUMMARY OF THE INVENTION

Generally speaking, in accordance with the present invention, a new acoustic insulating material, especially for sound dampers of compressed air devices, is provided. The inventive material overcomes disadvantages associated with conventional acoustic insulating material and enables the construction of a sound damper in the form of a kitted fabric roll for compressed air devices which offers improved noise or sound damping.

The present invention embodies an insulating material comprising a knitted fabric tube made from fibres and rolled up to form a knitted fabric roll. According to the present invention, plastic fibres having a larger surface area than conventional fibre structures are used because the outer cross-sectional contour of the fibres has a geometric shape differing from that of the round outer form.

According to advantageous embodiments of the present invention, the enlargement of the surface area of the fibre is achieved by regularly or irregularly profiled fibre cross-sectional contours, especially by a cruciform or stellate fibre cross section.

According to one embodiment of the present invention, an enlargement of the surface area can also be achieved by an embossed, regular or irregular structure or profiling of the surface of the fibre in longitudinal direction of the fibre.

The foregoing approaches for increasing the surface area according to embodiments of the present invention can also be combined.

Still other objects and advantages of the present invention will in part be obvious and will in part be apparent from the specification.

The present invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in greater detail hereinafter on the basis of the accompanying drawings, wherein:

FIG. 1 shows a fibre with cruciform cross section in accordance with one embodiment of the present invention,

FIG. 2 shows a fibre with stellate cross section in accordance with another embodiment of the present invention,

FIG. 3 shows a fibre with an irregular stellate cross section in accordance with yet another embodiment of the present invention,

FIG. 4 shows a fibre with surface profiling in the longitudinal direction in the form of alternating thick and thin cross-sectional regions in accordance with a further embodiment of the present invention,

FIG. 5 shows a fibre having a cross-sectional profile similar to the fibre depicted in FIG. 1 with additional longitudinal profiling in accordance with a still further embodiment of the present invention, and

FIG. 6 shows a fibre having a cross-sectional profile similar to the fibre depicted FIG. 2 with additional longitudinal profiling in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention, an acoustic insulating material, especially for a sound damper in compressed air devices, is provided which includes fibres of a thermoplastic material comprising structures or profiled elements which are moulded or embossed in the surfaces thereof and which raise the surfaces or specific surfaces thereof. The fibres are processed to form braided or woven tubing, the ends thereof being welded such that an approximately rectangular tubular section is created, forming the acoustic insulating material when rolled into a woven tubular element.

Referring now to the drawings, FIG. 1 shows a fibre 2 having a cruciform cross section; FIG. 2 shows a fibre 4 having stellate cross section; and FIG. 3 shows a fibre 6 having irregular stellate cross section. Such cross-sectional shapes as illustrated in FIGS. 1 to 3 can be produced from thermoplastic plastic materials by known pultrusion methods.

FIG. 4 shows a fibre 8 with round cross section, for example, albeit with surface profiling 10 in longitudinal direction in the form of alternating thin regions 12 and thick regions 14 of the cross section, which regions can also be regularly or irregularly structured. Enlargement of the surface area of the fibre can also be achieved by this measure.

FIGS. 5 and 6 show fibres 16, 18 having cross-sectional profiles akin to the fibres depicted in FIGS. 1 and 2, respectively, with additional longitudinal profiling. This longitudinal profiling can be, for example, wavelike profiling 20 (FIG. 5), or tooth-like profiling 22 (FIG. 6).

Polypropylene, polyethylene and other thermoplastic materials are suitable as the material for fibres 2, 4, 6, 8, 16, and 18. The surface profiling in longitudinal direction of the filament can be imprinted or impressed in the surface of the fibre by suitable dies after the continuous fibre has emerged from the orifice of the die.

Fibre surface area has, heretofore, not been taken into consideration. It was found that, with a sound damper in which insulating material in the form of a knitted fabric roll containing a fibre with increased surface area in accordance with the present invention is used, considerably greater sound damping is achieved than in the use of conventional knitted fabric rolls.

Better absorption of airborne sound is achieved by the present invention. The acoustic energy is converted to dissipation energy. The efficiency is increased by the larger surface area of the fibre. The improved sound damping permits the use of smaller sound dampers, so that a cost reduction can be achieved and less installation space is needed. Conventional knitted fabric rolls in existing sound dampers can be replaced by knitted fabric rolls containing the acoustic insulating material according to the present invention.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween. 

1. An acoustic insulating material, comprising at least one fibre of thermoplastic material, said at least one fibre including at least one of structure formed on and contouring of a surface thereof to increase at least one of surface area and specific surface area of said fibre.
 2. The acoustic insulating material according to claim 1, wherein said at least one fibre is formable into at least one of a braided fabric and knitted fabric tubing section, ends of said tubing section being sealable to form an approximately rectangular tubing portion, said tubing portion being rollable into a fabric roll.
 3. The acoustic insulating material according to claim 1, wherein said at least one fibre has a cruciform cross-sectional shape.
 4. The acoustic insulating material according to claim 1, wherein said at least one fibre has a stellate cross-sectional shape.
 5. The acoustic insulating material according to claim 1, wherein said at least one fibre has an irregular stellate cross-sectional shape.
 6. The acoustic insulating material according to claim 1, wherein said at least one of structure on and contouring of said surface of said at least one fibre extends in longitudinal direction.
 7. The acoustic insulating material according to claim 6, wherein said at least one of structure on and contouring of said surface of said at least one fibre effects alternating cross-sectional thin zones and cross-sectional thick zones of said at least one fibre.
 8. The acoustic insulating material according to claim 7, wherein said at least one of structure on and contouring of said surface of said at least one fibre is effected at least one of regularly and irregularly.
 9. The acoustic insulating material according to claim 1, wherein said surface of said at least one fibre includes further contouring extending in longitudinal direction that does not affect the cross-sectional shape of said fibre.
 10. The acoustic insulating material according to claim 9, wherein said further longitudinal contouring has at least one of a wavelike and tooth-like shape.
 11. The acoustic insulating material according to claim 2, wherein said fabric roll forms at least a part of a sound damper for a compressed air device.
 12. The acoustic insulating material according to claim 1, wherein said thermoplastic material is polypropylene.
 13. The acoustic insulating material according to claim 1, wherein said thermoplastic material is polyethylene. 